Feed mechanism for cartridge belts



y W45. G. c. GENTRY ET AL FEED MECHANISM FOR CARTRIDGE BELTS Filed Feb. 16, 1942 3 Sheets-Sheet l GEORGE ae/vnev M 8. 504 s y 1945. G. c. GENTRY ET AL 2,375,219

FEED MECHANISM FOR CARTRIDGE BELTS Filed Feb. 16, 1942 3 Sheets- Sheet 2 M/A/E 6. 604 s 4 clams/ y 1945- G. c. GENTRY ET AL 2575,2119

FEED MECHANISM FOR CARTiUDGE BELTS Filed Feb. 16, 1942 5 Sheets-Sheet 3 Patented May 8, 1945 FEED MECHANISM FOR CARTRIDGE BELTS George C. Gentry, Pittsburgh, Pa., and Wayne S. Boals, Dayton, Ohio Application February 16, 1942, Serial N 0. 431,136

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 3'70 0. G. 757) The invention described herein may be manu- Claims.

factured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to improvements in car tridge belt feed mechanisms of the type which are actuated either by the recoil or the counterrecoil movement of an automatic or machine gun. Among other objects the invention aims to provide means for preventing jamming of the cartridge belt; means for preventing reverse feed or backslippage; means for preventing overdrive; and means for compensating for overtravel of the driving means. A further object is to provide a cartridge belt feed mechanism which may be adapted readily to either right or left hand feed. Other objects will appear from the following description of the preferred embodiment of the invention shown in the accompanying drawings, wherein Fig. 1 is a plan view of the mechanism with part of the cover shown broken away and parts of the machine gun indicated in dot and dash lines;

Fig. 2 is a section on line 2-2 of Fig. 1;

Fig. 3 is a section on the line 33 of Fig. 1;

Fig. 4 is a section on the line 1- of Fig. 1;

Fig. 5 is a section on the line 5-5 of Fig. 1;

Fig. 6 is an end elevation, with parts broken away, and part of the machine gun being shown in dot and dash lines;

Fig. '7 is a detail in section;

Fig. 8 is a fragmentary perspective of the main feed ratchet and part of the feeding spool;

Fig. 9 is a plan view of the pawl which actuates the spool;

Fig. 10 is a side elevation of the same;

Fig. 11 is an end elevation of a cam;

Fig. 12 is an elevation of a pawl or stop;

Fig. 13 is an elevation from the right side of Fig. 12; and

Fig. 14 is an exploded view of the adjustment means for the cam of Fig. 11.

Referring articularly to the drawings, 53 designates the receiver, 54, the Edgewater adapter and E5, the stationary portion of the adapter of a well known machine gun. Parts 63 and 6-2 constitute the recoil and counterrecoil. portion of the gun. Bracket 62 is welded to stationary portion 65 and provides an anchorage for a linkage (to be described) which may operate the cartridge belt feed when the parts 63 and 64 counterrecoil. To form a frame for the belt feed mechanism, mounting plate I (Fig. 1) has end plates 2 and 3 secured thereto at right angles by screws 5 and lock washers 5. Lugs 5 and 1 are integral with the mounting plate and each has a bore 8 (Fig. 6) for the standard pin 9 which also slidably fits bores in lugs (not shown) on receiver 63. Thus pin 9 unites the frame of the belt feed mechanism with the machine gun feedway but permits quick detachment when it is necessary to inspect or repair the feed mechanism or the gun. It will be understood that the same connection may be made at the other side of the gun, i. e., feed may be either from the right or left side.

To support the belt feeding spool and other parts of the mechanism, a fixed axle Ill (Fig. 2) has an enlarged head lila and is keyed near the head by pin 1 3 passing through slot H in end plate 3. The other end of the axle passes through a bushing I4 fixed in end plate 2 and extends outside of the end plate where it is screw threaded as indicated at l5 and is further secured by means of washer Hi, nut i1 and cotter pin l8. Feeding spool I9 rotates freely on the axle and has two disks 20. 2| each with ten notches or recesses a, Zia respectively for laterally receiving the cartridges (not shown) carried by the belt (not shown). As the feeding spool per se is more or less conventional further description of the details of its construction will be omitted. A washer 22 preferably holds the spool slightly spaced from end plate 3 and hence properly located on the axle.

To impart the necessary step-by-step motion to the feeding spool, a pawl and ratchet mechanism is provided. The ratchet comprises a toothed disk 3%] (Figs. 1, 2, 4, and 5) rotatably mounted on axle Ill and having a hub 33 provided with an annular series of teeth 33a which mesh with like teeth 23a, on the hub 23 of feeding spool IS. The two annular sets of teeth 23a, 33a form an adjustable means for driving engagement of the ratchet disk and the feeding spool. Preferably there are nineteen teeth in each set 23a, 33a; hence there are nineteen different angular positions which any one of the ten cartridge-receiving notches or recesses 28a, Zia may assume relative to a tooth on disk 30. On its periphery disk 30 has ten equally spaced ratchet teeth 3| each formed as best shown in Fig. 8 with the end face 32 of each tooth extending radially outwardly and also laterally from the smaller end of the tooth adjacent thereto. Each tooth face 32 is thus L-shaped to provide two surfaces for engagement by a pawl id to be described. To prevent back.- slippage, a pawl 34 (Fig. 4) is pivoted on a bracket 35 (welded fast to the face of mounting plate l) by means of a pin 36. To hold pawl 34 in contact with the periphery of the ratchet disk $0, thereby to engage tooth surfaces 32 successively, a spring 38, best shown in Fig. 1, presses against the outer edge of pawl 34. It should be emphasized that pawl 34 does not participate in the drive of the ratchet 3|), but merely prevents backslippage or retrograde movement of the feeding spool exceeding one-tenth of a revolution (36), which is the amount of movement required to feed one cartridge.

To operate ratchet 3U, pawl 44 is carried on the end of an arm 4| (Fig. '7) preferably integral with a pinion segment 4! both arm 4| and pinion segment 40, being carried by a sleeve or collar 39 which is free to oscillate on axle In. Pinion segment meshes with a rack (Figs. 2 and 6) slidable in a guide 5| secured by screws 52 to the inner face of end plate 2. Rack 50 has a yoke 54 at one end and a pivot pin passes through said yoke and through one endof a link 4 53. The other end of link 53 is pivotally connected to the long arm of a bell crank lever 56 by means of a pin 51 and cotter pin 58. Bell crank lever 56 is pivoted as at to a yoked bracket 59 welded to the outer face of end plate 2, as shown in Figs. 1 and 2. The short arm of the bell crank lever is pivotally connected to a double yoked link 6| by a pin 51a, and link 6| is pivoted as at 5112 to bracket 62 which is stationary because welded to the stationary portion of the adapter of the machine gun. Obviously as the feed assembly reciprocates with the movable portion '53 of the gun, link 6| will oscillate slightly, bell crank lever 56 will oscillate on its pivot axis, link 53 will reciprocate (and also oscillate), and rack 50 will reciprocate to cause oscillation of arm 4| and hence ratchet-driving movement of pawl 44. 'The described linkage is also adapted to operate the feeding spool upon recoil of the gun, since the parts can easily be arranged to operate reversely. Since there are ten teeth 3| to be engaged by pawl 44 as will be described, the total movement or stroke of arm 4| should slightly exceed 36 (one-tenth of a revolution).

As shown in Fig. '7, pawl 44 is slidable in a slot 43 cut in a cylinder 42 secured to the free end of the oscillatory arm 4|. In cross section pawl 44 may have the shape of a keyhole, a shown in Fig. 5. A coil spring 43 fits in a recess 45 formed in one end of pawl 44, the other end of spring 48 abutting the inside end wall of the cylinder 42 and thus tending to hold the pawl extended relative to the cylinder and at right angles to arm 4|. The ratchet-engaging end of pawl 44 has cam, followers 46 and 41. Referring to Figs. 9

and 10, cam follower 45 has a leading face 46a Because of variations in the recoil and counterteeth Ila on a ring 11 which is loose on the axle. Ring Tl has another annular set of teeth 11b on its other end, but there are twenty of the latter, to mesh with twenty teeth 18a on fixed ring 18, the latter being secured to axle I!) by means of a, pin 14 passing through hole 15 drilled in the axle. By progressive shifting of the double sets of teeth 16a, 11a, Nb and 18a, three hundred and eighty different angular adjustments or settings of the cam 61 may be obtained. In short the described construction permits an angular adjustment of the cam on the supporting axle of slightly less than 1, or of any larger angle desired. This angular adjustment makes it possible to bring the end of pawl 34 practically into engagement with tooth surface 32 whenever the parts are initially adjusted as when loading.

On the outer face of disk sector or cam 51 a series of arcuate, concentric cam surfaces are formed, namely, a level cam portion 69, a sloping cam portion It, a level cam portion 1|, a sloping cam portion 12 and a level cam portion 13. The angles subtended by arcuate cams 69 to T3 inclusive are designated a", b", c", d and e respectively. In the illustrative form of the invention, the arcuate cam 61 may have the level portions 69 and 13 of equal arcuate length and spaced /3 inch from the level portion 1|, which is the middle of the cam. In other words the cam 61 will effect a movement of inch of the cam follower 44 whose end surface 41' rides on the cam due to pressure of spring 43.

At least two abnormal operations of the mechanism may result in material overtravel of arm 4|. Let it be first assumed that the critical po sition of arm 4| is advanced (i. e., moved counterclockwise) slightly in excess of 36 as compared with the position of Fig. 6. In the absence of means to prevent or compensate for overtravel of the driving means. the leading face 46a would thereupon engage the driven face of ratchet tooth 3! adjacent thereto. Thereafter each stroke of arm 4| would result in the attempted delivery to two loaded cartridges into the machine gun, resulting in immediate jammin of the cartridge belt. However, with the parts as above described, cam face 4'! maintains a positive separation between the leading face of cam 44 and the driven face of any one ratchet tooth 3|, whenever the cam face 41 is in contact with cam portion 69 (Fig. 5). But when the cam face 41 moves along cam portion H! to central cam portion H, the leading face of cam portion 46 has moved into complete operable alignment with the driven face of the ratchet tooth 32 immediately adjacent in a clockwise direction. Cam portion 47 will not alter said operable alignment as arm 4| completes its stroke. Then the pawl 34 seats itself against a ratchet tooth 3| and arm 4| is ready for return to its starting position. By the described construction pawl 44 can only move the spool l9 through 36 (one tooth length) regardless of whether the mechanism is operated by recoil or counterrecoil and regardless of the extent of such movement (if equal to that required for 36 movement).

While there are instances in which means for preventing overdrive (the effect of monentum of the loaded spool) is not required, the provision of such means nevertheless forms a part of our invention. Ratchet disk (Fig. 3) has ratchet teeth 8|, ten in number, on its periphery but with their working faces disposed oppositely to the working faces of teeth 3|, see Fig. 4. A pawl 19, pivoted by pin 36 upon bracket 35, is urged toward engagement with teeth 8! by means of spring 86. Extending from the middle portion of pawl 19 is a pin projection 85. Ratchet disk 88 is angularly adjustable with respect to. ratchet disk 30 by means of several screws or bolts 83 passed through arcuate slots 82 in disk 88 and locked by lock washers 84 (Fig. 2). Assuming that arm 4| is poised for the down stroke, as shown in Fig. 5, screws 83 are loosened to permit counter-c1ock- Wise shifting of ratchet disk 80 until an angular gap f" (Fig. 3) is created between the end of pawl '19 and the nearest ratchet tooth face. Then screws 83 are tightened. As will be understood from Figs. 5 and 12, the end of pawl 19 is then raised clear of the oncoming ratchet teeth 8! because of contact between the tip portion of the pin projection 85 and the outwardly facing surface of cam 49, so that the driving means 4| is free to swing downwardly (i. e., c1ockwise) slightly in excess of 36 from the position of Fig. 6. As cam 49 moves away from pin projection 85 the end of pawl 19 automatically engages the next tooth 8|. Angular gap 7 is made just large enough to assure the engagement of pawl 34 with tooth 3! upon completion of the stroke arm 4i. By the described mechanism, the tendency of the loaded spool to keep moving due to its momentum is completely checked.

As shown in Figs. 1, 2 and 6, the forward and rear end plates 2 and 3 are provided with a closely fitting half cover 81 having a rearwardly overhanging inclosed portion 88 (Fig. l). The lower or entry portion of cover 8'! is provided with a flared out mouth 89 for accommodating any slight misalignment of the upwardly traveling loaded cartridge belt. Cover 81 is secured by a plurality of screws 99, with lock washers (not shown) if desired.

Feeding spool 19 is loaded by simply inserting the uppermost cartridge in the teeth of disks 20 and 2| which are adjacent the mouth 89, and then pushing the leading portion of the belt until the cooking mechanism of the machine gun is able to engage the lead cartridge. Where the overdrive prevention means of-Fig. 3 is employed, care must be taken to assure elevation of pawl 79 substantially as shown in Fig. 5, either by forcing the machine gun into the recoiled position of Figs. 1 and 2 or by otherwise lifting pawl 19 out of engagement with the teeth 8 I.

Although the above description is specific to a certain structure, it will be understood that there may be departures therefrom which will still clearly fall within the field and scope of the subject invention, and we therefore do not wish to be restricted thereto, but only in so far as the appended claims are so limited.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. In a cartridge feed mechanism for recoiling guns, said feed mechanism of the type comprising an axle, a feed spool mounted thereon, a ratchet wheel fixed to said spool and a pawlconstructed and arranged for moving said ratchet Wheel in response to the moving parts of the gun, a second ratchet wheel mounted on the spool for pawl engagement in a sense 'contrariwise to that of the first mentioned ratchet wheel, a suitable pawl engaging said second ratchet wheel for inhibiting overdrive of the spool, and a third pawl mounted in opposition to the first mentioned pawl for inhibiting retrograde motion of the spool by engagement with the first mentioned ratchet wheel, the improvement comprising cam means fixed with relation to the said axle and positioned for actuating the first mentioned pawl to disenage the same from its ratchet wheel when the pawl has moved through a distance equal to the unit ratchet spacing.

2. A mechanism asset forth in claim 1, said cam means constructed and arranged for adjustment with respect to the first mentioned ratchet wheel.

3. A mechanism as in claim 1 wherein said cam means comprises a double tooth ring connection with the fixed part of said mechanism the number of teeth on one face of the ring being very nearly equal to the teeth on the other face of the ring whereby fine adjustment of the angular position of the cam means with respect to the ratchet wheel is obtained.

4. A mechanism as in claim 1 wherein said cam means comprises a .double toothed ring connection with the fixed part of said mechanism the 'number of teeth on one face of the ring being very nearly equal to the teeth on the other face of thering whereby fine adjustment of the angular position of the cam means with respect to the ratchet wheel is obtained, and an adjustable connection between the spool proper and the ratchet wheels for adjusting the angular relation of the spool thereto.

5. A mechanism as set forth in claim 1 said first mentioned ratchet wheel comprising a top face and a side face on its teeth and the said first mentioned pawl being positioned parallel to the spool axle and comprising a portion for engaging the top face of the ratchet teeth and a portion for engaging the said cam means, said cam means being arcuate to correspond to the sweep of the pawl and having a connection with the first mentioned ratchet means for angular adjustment with respect thereto, and means within said pawl for biasing the same to ratchet engaging and cam engaging position.

GEORGE C. GENTRY. WAYNE S. BOALS. 

